Vehicles driven with an electric motor serving as a driving source are conventionally known, such as hybrid vehicles, electric vehicles and fuel cell vehicles. Such a vehicle is equipped with a power storage device such as a battery for storing electric power supplied to the electric motor.
Recently, there have been proposals for configuring a vehicle as mentioned above such that a power storage mechanism is charged from a power supply external to the vehicle, such as a power supply at a house (hereinafter simply referred tows an external power supply as well). Specifically, the power storage device (battery) of the vehicle is charged with electric power supplied from a power supply at a house by coupling a receptacle provided at the house and a connector provided for the vehicle with a cable. Hereinafter, a vehicle whose power storage device such as a battery mounted on the vehicle is chargeable from a power supply external to the vehicle shall be referred to as a “plug-in vehicle” as well.
Japanese Patent Laying-Open No. 10-136570 (Patent Document 1) discloses a charging device mounted on an electric vehicle. This charging device includes a DC/DC converter performing DC-DC conversion on a received direct current (DC) voltage to output the converted voltage, and charging-mode control means. The charging-mode control means electrically disconnects a motor from the DC/DC converter when a battery is charged with electric power from an external power supply. Further, the charging-mode control means causes a voltage from the external power supply to enter the DC/DC converter directly or indirectly, such that a DC voltage output from the DC/DC converter is applied to the battery.    Patent Document 1: Japanese Patent Laying-Open No. 10-136570    Patent Document 2: Japanese Patent Laying-Open No. 2002-84676    Patent Document 3: Japanese Patent Laying-Open No. 9-233710